Remove MANIFEST.in
Remove MANIFEST.in

pbr is able to generate the file listing for us, and this file is bugged
as it misses files like alembic.ini. Let's remove it.

Fixes-Bug: #1231503

Change-Id: I95204db0752a10138d3e3d7bc1fa9a271145bf67

rackerlabs/instrumented-ceilometer,JioCloud/ceilometer,idegtiarov/ceilometer,eayunstack/ceilometer,redhat-openstack/ceilometer,mathslinux/ceilometer,NeCTAR-RC/ceilometer,citrix-openstack-build/ceilometer,NeCTAR-RC/ceilometer,MisterPup/Ceilometer-Juno-Extension,mathslinux/ceilometer,tanglei528/ceilometer,pkilambi/ceilometer,citrix-openstack-build/ceilometer,rackerlabs/instrumented-ceilometer,tanglei528/ceilometer,NeCTAR-RC/ceilometer,chungg/aodh,ityaptin/ceilometer,redhat-openstack/ceilometer,fabian4/ceilometer,idegtiarov/ceilometer,openstack/aodh,Juniper/ceilometer,rickerc/ceilometer_audit,sileht/aodh,MisterPup/Ceilometer-Juno-Extension,pczerkas/aodh,eayunstack/ceilometer,JioCloud/ceilometer,cernops/ceilometer,openstack/aodh,openstack/ceilometer,citrix-openstack-build/ceilometer,fabian4/ceilometer,luogangyi/Ceilometer-oVirt,rickerc/ceilometer_audit,chungg/aodh,sileht/aodh,maestro-hybrid-cloud/ceilometer,openstack/ceilometer,rackerlabs/instrumented-ceilometer,pczerkas/aodh,pkilambi/ceilometer,JioCloud/ceilometer,cernops/ceilometer,tanglei528/ceilometer,ityaptin/ceilometer,froyobin/ceilometer,isyippee/ceilometer,Juniper/ceilometer,maestro-hybrid-cloud/ceilometer,m1093782566/openstack_org_ceilometer,rickerc/ceilometer_audit,luogangyi/Ceilometer-oVirt,r-mibu/ceilometer,isyippee/ceilometer,r-mibu/ceilometer,m1093782566/openstack_org_ceilometer,froyobin/ceilometer